Gingival tissue retraction device and method

ABSTRACT

A method and a device for effecting the cordless retraction of the gingival sulcus tissue that includes a dam shaped to be fitted onto a tooth. In one embodiment, the well of the dam is pre-filled with a predetermined amount of a flowable retraction material having a heavy viscosity or putty consistency. In another embodiment a hydrophilic material is added. The preloaded tooth dam is fitted to a prepared tooth so that when pressure is applied onto the tooth dam, the retraction material is displaced under pressure and forced into the sulcus, causing the gingival tissue to retract away from the tooth to enlarge the gingival sulcus. In another embodiment the cap is filled with a dilatant material. In another embodiment, the cap is filled with an impregnated compressible porous material. In yet another embodiment, the cap is pre-dosed with an astringent or hemostatic agent.

RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 11/825,802 filed Jul. 9, 2007, now U.S. Pat. No. 7,942,669, which isa continuation in part of International application No. PCT/US2007/08232filed Mar. 30, 2007, which is a continuation in part application of U.S.application Ser. No. 11/398,134 filed Apr. 5, 2006 now U.S. Pat. No.7,241,143.

FIELD OF THE INVENTION

This invention is directed to a method and device for effectingretraction of tissue, and more specifically to a method and deviceutilizing a dam pre-filled with a flowable retraction material foreffecting the retraction of gingival tissue in preparing a tooth for thetaking of an impression of the tooth necessary for making a crown orbridge dental prosthesis. In a more specific embodiment of theinvention, the dam is provided with a retentive surface whereby theretraction material adheres to the retentive surface of the dam tofacilitate the removal of substantially all of the retraction materialfrom the retracted gingival tissue upon the removal of the dam.

BACKGROUND OF THE INVENTION

The traditional method for retracting gingival tissue prior to thetaking of an impression of a prepared tooth to form a crown or bridge isto mechanically pack a small length of cord saturated with or without anastringent about the base of the tooth to enlarge the gingival sulcusspace about the base of a tooth. After a period of time, the cord isremoved from the enlarged space defined about the base of the tooth.Upon the removal of the cord, it frequently happens that coagulum formedto stop the bleeding or seepage of fluid is removed with the cord toresult in the seepage of additional bleeding into the space. As aresult, an impression cannot be made of the prepared tooth until theadditional bleeding can be controlled or stopped. Thus, the traditionalprocedure for enlarging the space between the gum and the base of thetooth necessary for taking an accurate impression is tedious, timeconsuming and painful or extremely uncomfortable for the patient. Also,there exists the danger that the dentist may accidentally force the cordbeyond the physiologic limit of the space to create a potentialperiodontal pocket which can cause the tooth to be eventually lost. Thegeneral practice of using the cord technique is relatively difficult andtedious for the dentist.

In the event that the space between the tooth and the gum that has to beretracted is very small, it becomes even more difficult for the dentistto place the cord without injuring the gum tissue and from forcing thecord beyond the physiologic limit, and renders the procedure morepainful for the patient. Further, the placing of the cord is not aprocedure which the dentist may delegate to a dental assistant or dentalhygienist. Also, the packing of a retraction cord is a most dislikedstep to perform during a crown or bridge restoration procedure.

Efforts have been made to obviate the noted disadvantages of affectingthe retraction of the gingival tissue by the use of a cord. One suchknown effort is the use of a kaolin type material that is mixed with anastringent salt which is simply placed about a prepared tooth to absorbthe moisture to cause the gum tissue to shrink. Such a product ismarketed by Sybron Dental Specialties under the brand name ExpaSyl.

It has been noted that such kaolin type material is packaged in acartridge similar to a typical anesthetic cartridge commonly used in adental office that requires the cartridge to be used with a syringe. Theend of the cartridge is pierced with a needlelike cannula and the forceof the syringing pressure is required to extrude the clay like kaolinmaterial through the cannula. Because of the density of the kaolin typematerial, the cannula requires the opening to be very large so as toenable the kaolin type material to flow therethrough. The large guageopening of the cannula renders the bending of the cannula difficult andwhich bending is often required in order to place the material indifficult to reach places within a patient's mouth. Because the openingof the cannula is quite large, difficulty is encountered in placing thekaolin type material about the gingival sulcus in a manner similar tothe traditional method of packing cord to retract the gum tissue.

Also, the use of such kaolin type material to retract the gum tissuetends to crumble, rendering it difficult to place in the space betweenthe gum tissue and the tooth to attain the desired retraction of the gumtissue. Another noted problem with such kaolin type material is theremoval of the kaolin material after the period of time required toaffect the hemostatic and the retraction. Generally, the kaolin materialis required to be washed out using a water-air spray with extreme careto remove all the kaolin material without restarting any bleeding in thegingival sulcus.

Another known technique for effecting a non-cord retraction and/orhemostatic is disclosed in U.S. Pat. No. 5,676,543. Therein disclosed isa generally two part process utilizing two different viscosities of asilicone material to effect the cordless retraction and/or hemostatic ofthe gingival sulcus.

U.S. Pat. No. 6,890,177 discloses a more simplified cordless retractionmethod and device whereby the cordless retraction may be accomplished byresorting to a porous sponge or foam cellular dam which is shaped toconform with the prepared tooth or teeth, arranged to contain a two partsilicone type impression material that includes a base portion and acatalyst, whereby the patient's biting force is utilized to apply thenecessary pressure to effect the desired retraction.

Other devices and methods are used to retract the gingival sulcus e.g.Magic foam cord which is dependent upon an expanding silicone materialwhich is a two-part, chemically cured component system that are requiredto be mixed by the dentist at chair side prior to application and whichcures or sets to effect the retraction of the gingival tissue.

This invention is directed to an improvement to the non-cord retractiondevices and procedures described hereinabove for effecting cordlessretraction of the gingival tissue by utilizing a dam that has beenpreloaded with the retraction material.

SUMMARY OF THE INVENTION

An object of this invention is to provide a much simplified cordlessretraction method and device for enlarging the gingival sulcus spacebetween the gum tissue and the prepared tooth prior to the taking of animpression for making a crown or bridge.

Another object is to provide a dental dam capable of retaining theretraction material thereto for effecting ease of removal of theretraction material after effecting the cordless retraction and/orhemostatic of the gingival sulcus of a prepared tooth prior to thetaking of an impression.

Another object is to provide for a hemostatic and/or cordless retractionof the gingival sulcus using the patient's own biting pressure to forcethe retraction material into the space between the gum tissue and theprepared tooth to enlarge the same.

Another object is to provide a cordless hemostatic and/or retractionmethod which is positive in operation and simple to perform.

Another object is to provide for a cordless hemostatic and/or retractionmethod of the gingival sulcus area, which is painless, comfortable andeasy on the patient, and easy for the dentist to perform.

Another object is to provide a single step device and method to effect agingival cordless retraction procedure.

Another object is to provide a dental dam initially preloaded with apredetermined amount of a flowable and pliable retraction materialconfined within the dental dam which can be readily fitted to a preparedtooth whereby cordless retraction of the gingival tissue is effectedsimply by the patient exerting a biting force on the dam.

Another object is to provide a dental dam formed of a retentive materialthat is pre-filled with a predetermined amount of a suitable, flowable,moldable or impression like retraction material whereby the moldableretraction material is cohesive and adheres or bonds to the retentivedam to facilitate a substantially complete removal of the material fromthe enlarged sulcus upon completing the cordless retraction of thegingival tissue.

Another object is to provide a single step method and device forretracting the gingival tissue by utilizing a retentive dam pre-filledwith a flowable, cohesive and pliable moldable or impression-typeretraction material.

Another object is to provide a single step method or device forretracting the gingival tissue utilizing a dam pre-filled with aretraction material fortified with an astringent and/or a hemostaticagent.

Another object is to provide a simplified device for effecting cordlessretraction of the gingival tissue in the form of a light permeable dampreloaded with a light activated retraction, impression like material.

Another object is to provide a simplified device and method foreffecting the cordless retraction of the gingival sulcus by theutilization of a dam preloaded with only the base portion of a two-partchemically cured impression like retraction material.

It is yet another object of the invention to provide a tissue retractionsystem that is pre-dosed with an astringent or hemostatic agent andtherefore easy to use.

It is a feature of an embodiment of the invention that a non-settingmaterial having dilatant properties is used within the cap or dam.

It is another feature of an embodiment of the present invention that aretraction material comprising polydimethylsiloxane, astringent orhemostatic agent, dilatant silicone, and a hydrophilic agent is usedwithin the cap or dam.

It is another feature of an embodiment of the present invention that animpregnated compressible porous material is used within the cap or dam.

It is another feature of an embodiment of the invention a porous cap ispre-dosed with an astringent or hemostatic agent.

The foregoing objects and other features are attained by having aprepared tooth to be restored readied for the taking of an impressionthereof in preparation of making a crown or bridge. After the tooth hasbeen properly prepared and before a proper impression can be made, thegum tissue about the base of the tooth must be retracted to enlarge thegingival sulcus. In the event there is excessive bleeding, the bleedingcan be controlled or stopped by the injection of a suitable astringentabout the base of the tooth. Such astringent may include a hemostaticagent, e.g. aluminum chloride, ferric sulfate, ammonium aluminum sulfateand the like, applied to the cut tissue by syringing or other suitableapplicators.

Where bleeding is slight or minimal, it may not be necessary to applyany astringent. After the controlled hemostatic, a dam having a well,groove or trough pre-filled with a predetermined amount of a retractionmaterial, e.g. a silicone type impression material which may also befortified with a hemostatic agent. A predetermined amount of theretraction or silicone impression material may also be optionally placedabout the entire circumference of the prepared tooth at the gingivalsulcus margin, preferably by syringing. The application of additionalretraction material may also be optionally generously applied to coverthe entire prepared tooth. The dam filled with the retraction orsilicone impression material is then placed over the tooth, at whichtime the patient is instructed to apply a biting pressure onto theretention dam and to maintain the biting pressure thereon for apredetermined time period sufficient for the silicone material to set,e.g. 3 to 7 minutes. In one form of the invention, the well of the dammay be provided with a retentive surface to which the retractionmaterial may adhere so that upon the removal of the dam, the retractionmaterial adhered thereto may also be removed. Upon removal of the damand retraction material, the tooth may be lightly washed and examined inpreparation of the taking of the impression. If additional retraction ofthe gum tissue is required, the procedure may be repeated.

This invention further contemplates that the dam having a retentivesurface may be formed of a natural or synthetic porous or cellularmaterial, e.g. a cellular, porous or grooved plastic, or a fibrousmaterial for defining a surface capable of retaining a retractionmaterial bonded thereto. The fibrous material may be either naturaland/or synthetic, e.g. woven or pressed cotton, rayon, nylon, linen andthe like, formed in the shape of a cap or sleeve which is arranged toencircle the prepared tooth or teeth. Such cap or sleeve is preferablypre-filled with a suitable moldable or impression, putty-like retractionmaterial, that is pliable, flowable and cohesive. When the cap or sleevepre-filled with such moldable or impression-type material is fitted ontothe prepared tooth and a biting pressure is applied onto the sleeve orcap, the flowable and pliable retraction material, which is confinedwithin the cap or sleeve, is forced under pressure into the gingivalsulcus to effect the retraction of the gingival tissue.

Due to the retentive nature or cellular structure of a retentive dam asdescribed herein, when a biting force is applied onto the cap or sleeve,also causes the moldable retraction material to permeate into the cells,porosity, or grooves defining the retentive surface of the cap or sleeveto mechanically adhere or bond to the inner retention surface of the capor sleeve. After the retraction of the gingival tissue has occurred, theretraction material adhered to the dam can be readily removed as the damis removed, leaving the gingival sulcus free of any residual retractionmaterial.

Retraction of the gingival tissue can be further enhanced by fortifyingthe moldable or impression-like retraction material with a suitableastringent/hemostatic agent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view of a prepared tooth prior to effecting thegingival retraction.

FIG. 1 is a side view of a prepared tooth and illustrating the placementof a hemostatic agent to control bleeding about the gingival sulcusarea.

FIG. 2 illustrates the filling of the groove of a dam for use onposterior teeth with an amount of impression-like retraction material.

FIG. 3 illustrates an intermediate step of placing the retractionmaterial about the gingival sulcus area.

FIG. 4 illustrates a generous application of the retraction materialcovering the entire prepared tooth.

FIG. 5 illustrates the step of placing the filled sponge or foam damonto the prepared tooth and the application of a biting pressurethereon.

FIG. 6 is a view similar to that of FIG. 5 to illustrate the retractionand enlargement of the sulcus space between the retracted gum tissue andthe base of the prepared tooth with the dam and impression materialremoved.

FIG. 7 illustrates a perspective view of a slightly modified sponge orfoam dam for use in the cordless retraction of the gum tissue aboutanterior teeth.

FIG. 8 is a cross-sectional view of another modification of a dental damaccording to the present invention.

FIG. 9 is a cross-sectional view of still another embodiment of thedental dam according to the present invention.

FIG. 10 is a perspective view of another modified form of the inventionhaving portions broken away.

FIG. 11 is a section view taken along section line 11-11 on FIG. 10.

FIG. 12 is a side section view of the embodiment of FIG. 10 as appliedto a prepared tooth to illustrate the retraction of the gingival sulcustissue.

FIG. 13 is a perspective view of another embodiment of the invention.

FIG. 14 is a perspective view of still another embodiment of theinvention.

FIG. 15 is a section view taken along line 15-15 on FIG. 14.

FIG. 16 is a section view of another modified form of the invention.

FIG. 17 is a perspective view of a series of frangibly connectedpreloaded dams embodying the present invention.

FIG. 18 is a section view of a modified form of a preloaded dental dam.

FIG. 19 is a perspective view illustrating another embodiment of thepresent invention.

FIG. 20 is a cross section of the embodiment of the inventionillustrated in FIG. 19.

FIG. 21 is a cross section of the embodiment of the inventionillustrated in FIG. 19 without any material.

FIG. 22 is an elevation view of the embodiment of the inventionillustrated in FIG. 19.

FIG. 23 is an elevation a view of the embodiment of the inventionillustrated in FIG. 22 turned ninety degrees.

FIG. 24 is a perspective view of another embodiment of the presentinginvention.

FIG. 25 is a cross section of the embodiment of the inventionillustrated in FIG. 24.

FIG. 26 is a cross section schematically illustrating another embodimentof the invention.

FIG. 27 is a block diagram illustrating the method steps of practicingan embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, there is shown in FIG. 1A a tooth 20 whichhas been prepared for receiving a crown or bridge, prior to effectingthe retraction of the gingival sulcus 21. However, before the impressioncan be taken for preparing the crown or bridge, it is imperative thatthe gingival sulcus tissue 21 be retracted in order for the dentist tomake an accurate impression of the prepared tooth 20.

In accordance with this invention and to control any excessive gingivalbleeding, an application of a liquid hemostatic agent 22, e.g. aluminumchloride, ferric sulfate or other suitable astringent is applied to thecut tissue in the area of the gingival sulcus. The astringent can beapplied with Centrix's Benda micro applicator 23 as seen in FIG. 1, orby any other suitable applicator, e.g. Centrix, Inc.'s BENDA® brush,SoftStix™ disposable applicator, or syringe, and the like. Theastringent 22 is applied with moderate pressure and by rubbing theastringent solution against the cut tissue to infuse the astringentsolution into the cut capillaries. After the bleeding is under control,a dam 24 is adjusted and fitted to the prepared tooth 20 or to at leastone tooth mesial and distal beyond the prepared tooth or teeth 20.

In accordance with this invention, the dam 24 is formed of a porous,cellular, foam, sponge like or rubber material which may be eithernatural or synthetic. The dam 24, as shown in FIG. 4, is formed for useon posterior teeth.

As shown, the dam 24 may be formed as an elongated block of a sponge,foam, rubber, or other type of porous, open or closed cellular material.It will be understood that the block of foam, sponge, porous or cellularmaterial may be of any desired length from which the dentist may severtherefrom the desired length necessary to dam one or more teeth beingworked upon. Conversely, the dam 24 may be pre-cut to size, dependingupon the number of teeth that may require gum retraction and to whichthe finished crown or bridge is to be applied.

As seen in FIG. 4, the dam 24 is provided with a longitudinally U-shapedgroove or trough 24A extending along the length thereof. The respectiveopposed side walls 24B and 24C and interconnected web or bottom 24D, asshown in FIG. 4, are sufficiently thick to contain a retraction materialfor exerting the necessary pressure to effect the gingival tissueretraction, as will be herein described.

FIG. 7 illustrates a modified block of sponge, foam, rubber, porous orcellular material from which a modified dam construction for use withanterior teeth is formed, as will be hereinafter described.

After the bleeding of the gum tissue to be retracted is controlled, thegroove 24A of an appropriate size dam 24 is filled with a hereinbeforedescribed silicone type impression-like retraction material 26, as shownin FIG. 2. The silicone type retraction material 26 may comprise atwo-part composition which includes a base portion and a catalystportion which, when mixed, will quickly set and become solid. The timeof setting can be varied within a predetermined time range bycontrolling the ratio of catalyst to base. Such silicones are availablefrom various manufacturers, e.g. CONQUEST by Pentron, EXAFLEX by G.C.,EXTRUDE by Kerr Corporation or IMPRESS and EXPRESS by 3M Corporation.While the silicone retraction materials are preferred, dental materialssuch as polyethers, polysulfides, wax or other moldable materials may beused. The condensation silicone materials are preferred. The siliconematerial 26 may be also fortified with between five percent (5%) totwenty percent (20%) by weight of a suitable astringent to aid in thegum tissue retraction and hemostatic. Any of the known astringents maybe used which are rendered compatible with the silicone. Some of theknown astringents or hemostatic agents are aluminum potassium sulfate,aluminum sulfate, ferric sulfate, aluminum ammonium sulfate or alum,ferric chloride, aluminum chloride, sodium chloride, zinc chloride andothers.

The same silicone material may also be applied about the gingival sulcusarea as shown in FIG. 3, preferably by syringing. The entire preparedtooth 20 may also be covered with the same silicone material as shown inFIG. 4. It will be understood that the step of applying the siliconematerial to the dam 24 or about the tooth as shown in FIGS. 3 and 4 canbe reversed. With the tooth covered with the silicone material 26, andwith the groove 24A of the dam 24 filled with the same siliconematerial, the silicone-filled dam 24 is placed onto the silicone coveredtooth, as seen in FIG. 5.

With the filled dam 24 disposed over the silicone covered tooth orteeth, the patient is instructed to apply a biting force or pressureonto the dam 22 as shown in FIG. 5, and to maintain the biting pressureon the dam 24 until such time that the silicone material sets,approximately 3 to 7 minutes. Upon setting of the silicone material, thedam 24 and the set moldable material is removed to expose the preparedtooth as shown in FIG. 6. As the dam 24 is formed of a porous, cellularor foam sponge-like material, some of the silicone material willpenetrate the retentive surface of the dam material, whereby the settingor curing of the silicone material causes the retraction material tomechanically adhere to the dam 24 so that the set retraction materialcan be removed in unison upon the removal of the dam 24. The tooth maythen be lightly washed, dried and examined to determine if the gumtissue has been sufficiently retracted so as to enable an accurateimpression to be made.

The bite pressure imparted by the patient onto the dam 24 as seen inFIG. 5, causes the silicone impression material to be forced into thegingival sulcus space, which together with the interaction of theastringent material causes the gum tissue in the gingival sulcus area toretract to enlarge the space 27 between the tooth and surrounding gumtissue as noted in FIG. 6. In the event additional retraction of the gumtissue is required, the procedure hereinabove described may be repeated.

While the porous, cellular, sponge or foam dams 24, as described herein,are preferred, it will be understood that other means may be used inlieu of the foam or sponge dams, e.g. rubber, silicone, plastic, acotton roll or hollowed cotton gauze or pad, or other suitable materialcapable of containing the retraction material, when the biting pressureis applied and maintained. The use of the biting pressure on the dam 24causes the silicone material, whether or not containing the astringentmaterial, to be forced onto the gingival sulcus space, causing the gumtissue to be retracted an amount sufficient to permit an accurate toothimpression to be made for making a crown or bridge.

While the method described is in reference to retracting the gum tissueof a posterior tooth, the same method is applicable for retracting thegum tissue of an anterior tooth. However, for an anterior gumretraction, the dam is preferably constructed with a V-shaped groove, asin FIG. 7.

Referring to FIG. 7, an anterior dam 28 may be severed from an elongatedblock 29 of foam or sponge like material similar to that hereinbeforedescribed, except the groove 30 is generally V-shaped as shown in FIG.7. The opposed sides of the V-shaped groove 30 converge inwardly of thefoam or sponge block. In all other respects, the construction of dam 28and the use thereof is similar to that described with respect to theconstruction and use of dam 24. It will be understood that the foammaterial, from which the described dams are made, may be formed of openor closed cells, natural or synthetic porous, foam or sponge typematerials.

However, when using closed cell foam or sponge material a retainer meansmay be needed to hold the retraction or silicone material within the damto facilitate the removal of the retraction material with the dental damupon completion of the gingival tissue retraction procedure.

FIGS. 8 and 9 illustrate dams having such a retainer means. In FIG. 8,the dam 124 has opposed side walls 124A and 124B interconnected by wall124D. At the intersection of the side walls 124A and 124B and the bottom124D are formed a retainer means in the form of undercuts 125A and 125B.The undercuts 125A and 125B help to retain the hardened, cured, orsolidified silicone, retraction paste, or impression material within thedam 124 upon the removal of the dam 124 from the tooth being treatedupon completion of the retraction procedure as herein described.

The undercuts 125A and 125B are particularly helpful when a closed cell,foam, sponge or molded part is used. A closed cell foam or sponge isadvantageous because of its rigidity. However, the closed cell foam doesnot have open cells for adhering thereto the solidified silicone,retraction, or impression material, thus making removal of theretraction material difficult. In such event, the undercuts 125A, 125Bprovide the structure for effecting the bonding of the retractionmaterial to the tooth cap for facilitating the removal of the retractionmaterial together with the removal of the tooth cap, upon the completionof the retraction of the sulcus tissue.

FIG. 9 illustrates another embodiment of a dam 224 having a retainermeans in the form of saw tooth shaped ridges 225A and 225B formed inside walls 224A and 224B, and which side walls are interconnected by aU-shaped bottom 224D.

The present invention may be sold in the form of a kit or packagecontaining the required components to practice the retraction method ofthe present invention. For example, the kit or package may contain aliquid hemostatic or astringent agent and an applicator for applying itto the sulcus. The kit or package may also contain the siliconematerial, retraction, or the impression material that can set, and adam. A delivery system may be included for use in applying a smallquantity of the silicone-type retraction or impression material aroundthe sulcus prior to the placement of the dam onto the tooth.

The method described and the dam for effecting the same are relativelysimple, expedient and results in a positive retraction of the gum tissueso as to ensure that all margins can be captured in a subsequentimpression procedure. The described invention further reduces the traumaand discomfort often encountered by the patient in a gum retractionprocedure. Also, the present invention provides enhanced results withmuch greater ease on both the dentist and patient. The procedure isrendered so simple that it can be delegated to a dental assistant.

It has been noted that prosthodontics has become very important aspeople are having longer and healthier lives. As a result,prosthodontics has become an important part of dentistry that willenable people to keep their teeth longer, if not for their entire lifespan. A major part of prosthodontics involves the replacement or repairof broken down, decayed, endodontic or severely worn down teeth. Adentist can now repair or replace such teeth with crowns or bridges. Alarge portion of the crown and bridge dental work is the repair orrestoration of a single tooth with an individual crown or, in lay terms,a “cap.” It has been estimated that approximately 80% of all crowns andbridge work involves the repair of a single tooth. While the inventionhereinafter described in reference to devices and methods of effectingcordless retraction of the gingival sulcus about a single tooth, it willbe understood that the described invention, in apparent modified forms,may also be adapted for retracting the gingival sulcus about multipleadjacent teeth.

The device and/or method to be hereinafter described is such that thecordless retraction of the gingival sulcus of a tooth or teeth can beaccomplished in a single step, as distinguished from those methods ordevices that requires a chemically curing retraction material consistingof multiple components that include a base portion and a catalystportion that require mixing by the dentist at chairside prior to use.The single step method or device as used herein means a tooth cap or damwhich is initially preloaded with a moldable retraction material whichis designed to fit onto a tooth without requiring the dentist to mixand/or pack the retraction material in the dam prior to the tissueretraction procedure.

As shown in FIG. 10, the tooth cap or dam 40 is designed and shaped soas to be fitted onto a single tooth 20 which is the subject of therestoration. In the illustrated embodiment, the tooth cap or dam 40includes a peripheral wall 41 which is formed of a porous or cellularmaterial, formed either of plastic or of natural or synthetic fibers,e.g. cotton, nylon, rayon and the like, which can be molded, woven,pressed or rolled so as to define a well or hollow 42 within theperipheral wall 41 of the tooth cap or dam 40. One end of the tooth capor dam 40 is closed by an end wall 43. Preferably, the closing end wall43 is formed of the same material that makes up the peripheral wall 41.It will be understood that material from which the tooth cap or dam 40is formed must be sufficiently rigid and have a limited amount ofelasticity so as to function as a dam for containing, confining anddirecting the retraction material 44 disposed therein toward thegingival sulcus when the tooth cap or dam 40 is used to effect acordless retraction of the gingival sulcus. As shown, the interiorsurfaces of the well or hollow 42 are laced with minute pores, cells orvoids, due to the nature of the material forming the tooth cap 40.

In accordance with this invention, the well or hollow 42 formed withinthe peripheral wall 41 is pre-filled with either a setting ornon-setting retraction material 44 that initially has a puttyconsistency, e.g. silicone, wax, acrylic or like material that has bothflowable and cohesive qualities that will not tear or break apart whenremoving the tooth cap or dam 40 from the tooth upon completion of agingival sulcus retraction procedure. The retraction material must be ofsufficient density so as to be capable of exerting the required pressurenecessary to effect the separation of the gingival tissue from the baseof the tooth when a biting pressure is applied onto the tooth cap or dam40 during a retraction procedure.

The retraction material 44 may comprise a light curable impressionmaterial such as methylmerthaculate or a light curable silicone. Othermaterials suitable for effecting cordless retraction of the gingivalsulcus include silicone, microcrystalline wax or other similarsubstances such as a “pillow soft” silicone made by McKeon Products orother manufacture, such as Dow Chemical.

The hollow or well 42 of the tooth cap 40 may also be pre-loaded withonly the base portion of a chemically cured impression-like, retractionmaterial. Such base portion of the chemically cured impression-like,retraction material will normally not set until treated or mixed withthe appropriate catalyst.

Preferably, the consistency of the base portion of the chemically curedimpression material should be akin to that of moldable putty.Pre-loading only the base portion of a chemically cured impressionmaterial into the well or hollow portion 42 of the tooth cap or dam 40will not set or cure over time. The “base component” of a chemicallycured impression material as used herein means that component orcomponents of an impression material that is free of any catalyst thatwould cause the base portion or component to set or cure, i.e. harden.

“Pre-filled” or “pre-loaded” as used herein is defined as having theretraction material placed into the tooth cap 40 or sleeve 60 in afactory or assembly facility so that the pre-filled tooth cap or sleeveis marketed or supplied to the dentist in a completely fabricatedcondition so that the “pre-filled” tooth cap can be used by the dentistwithout requiring the dentist to mix or pack the retraction materialinto a dam at chair side.

The advantage which the pre-filled tooth cap 40 has over the prior knownmethods of effecting cordless retraction is that the retraction of thegingival tissue can be effected in a more efficient and time-savingone-step procedure.

As indicated in FIG. 12, to effect the cordless retraction of thegingival tissue, the dentist need only place a pre-filled dental dam 40,as shown in FIG. 12, onto the tooth 20 to be restored and requesting thepatient to impart a biting pressure onto the closed end 43 of the toothcap or dam 40. As indicated by arrow A, the biting pressure impartedonto the closed end 43 of the tooth cap 40 will cause the closed end 43to deform as shown, causing the confined moldable retraction material 44to flow and exert a pressure about the entire base of the tooth wherebythe gingival sulcus tissue 21 retracts away from the tooth 20. Theexerted pressure forces the retraction material 44 between the tooth 20and the gingival tissue 21 to enlarge the sulcus 27 about the entirebase line of the tooth, as best seen in FIG. 12. In doing so, theretraction material 44 is also forced into the pores, cells or retentivesurfaces of the interior wall of the tooth cap 40 to form a mechanicalbond with the interior wall surface that defines the hollow or well 42.

The pressure imparted onto the tooth cap or dam 40, as shown in FIG. 12,is maintained for a predetermined period of time, e.g. 3 to 7 minutes,depending upon the amount of bleeding or oozing that may be occurring.As the applied pressure also causes the retraction material 44 to flowinto the pores, cells or retaining means formed on the interior surfacesof the well or hollow 42, the retraction material becomes bonded tointerior wall of the cap 40, which assures that the retraction materialcan be totally moved as the tooth cap 40 is released and removed fromthe tooth, to result in an enlarged sulcus substantially free of anyresidual retraction material 44. Thus, a dentist need not be required tophysically remove any residual retraction material from the sulcus space27 upon completion of the sulcus retraction procedure. As a result, anypossibility of injuring the delicate gingival tissue and restarting thebleeding which may occur in effecting the removal of residual materialfrom the enlarged sulcus is avoided.

If desired, a hemostatic and/or astringent agent may be incorporated inthe retraction material, as hereinbefore noted.

The retraction method now becomes a simple one step procedure. After atooth has been properly prepared for a crown or bridge, a properly sizedtooth cap 40, pre-loaded with a suitable retraction material as hereindescribed, is placed onto the prepared tooth 20, and the patient isinstructed to bite down on the tooth cap 40 and hold the biting pressurefor 3 to 7 minutes. Upon the expiration of said predetermined timeinterval, the patient releases the biting pressure, to permit thedentist to effect the removal of the tooth cap 40. In doing so, theretraction material when bonded to the walls of the hollow or well 42 isalso removed, leaving behind a clean space or sulcus about the tooth 20formed by the retraction of the gingival tissue 21. Thus, the time andtrauma to the patient is substantially reduced.

FIG. 13 illustrates a modified form of a pre-filled tooth cap 50embodying the invention. The tooth cap 50 is similar to tooth cap 40,except that tooth cap 50, adjacent the open end 50A, is provided with atransverse notch or cutout portion 51 which permits the notch or cutoutportion on opposite sides of the tooth cap 50 to complement or conformto the curvature of the gum line between adjacent teeth. In all otherrespects, the structure and method of use of tooth cap 50 is similar tothat describe with respect to tooth cap 40.

FIGS. 14 and 15 illustrate a further embodiment of a tooth cap. As shownin FIGS. 14 and 15, the tooth cap 60 is formed of a material similar tothat hereinbefore described, configured in the shape of a cylinder 61which is opened at the opposed ends 61A, 613. The cylinder 61 ispreloaded with a retraction material 62 as hereinbefore described. Ifdesired, it will be understood that one open end 61A or 613 of cylinder61 may be provided with a transverse notch or cutout portion similar tonotch 51 of FIG. 13.

If desired, the tooth caps described herein, e.g. tooth caps 40, 50, 60,or 80 may be formed in a chain or tree 70 having a frangible web ortear-line 72 connecting a series of adjacent tooth caps to one anotheras indicated in FIG. 17. The arrangement is such that a dentist canreadily separate an individual tooth cap 40 from its chain or tree 70along the frangible tear-line 72 as needed.

FIG. 18 illustrates another modified form of the invention. The toothcap 80 of FIG. 18 is similar to that hereinbefore described except thatthe interior surfaces 81 that define the boundaries of the well orhollow 82 are provided with a series of undercuts or notches 83 toprovide retention means to enhance the bonding or adhesive of theretraction material 81 to the interior surfaces of the tooth cap 80.

It will be understood that the tooth caps described herein may be madein different sizes and/or shapes to accommodate the size or shape of thetooth being restored.

The foregoing method may be practiced by using a retraction material,e.g. a non-curing silicone putty material or an equivalent thereofhaving a heavy viscosity preloaded in any of the described tooth caps40, 50, 60 or 80, as shown in the drawings. In the event any excessivebleeding or oozing is encountered, an astringent/hemostatic agent can beburnished into the gingival sulcus before the pre-loaded compressibletooth cap is placed over the tooth. The maintaining of the biting forceof the patient onto the tooth cap described herein for the predeterminedtime period, e.g. 3 to 7 minutes, should stop any bleeding, retract thegingival tissue, and widen the gingival sulcus 27, preparatory to thetaking of an impression for the fabrication of the appropriate crown orbridge.

In the event the retraction material preloaded into a cap 40, 50, 60 or80 as herein described is a light curable impression type material, itwill be understood that such dental dam be formed of either atransparent or light pervious material so as to permit the curing lightbeam to penetrate therethrough to set or cure the light curableretraction material contained therein.

In the event that the base portion only of a two-part chemically curedimpression or retraction material is preloaded in the described dentaldam dams 40, 50, 60, or 80, the dentist, prior to placing the preloadedcap onto the tooth, may apply a thin layer 63 of a catalyst onto theexposed surface of the base material 62, as shown in FIG. 16, so thatthe exposed portion of the retraction material 62, in contact with thecatalyst layer 63, may cure upon a lapse of a predetermined timeinterval, e.g. 3 to 7 minutes.

Preloading a tooth cap with a retraction material capable of eithersetting or curing or non-setting enhances both the enlarging of thesulcus and the maintaining of the enlarged sulcus to insure the makingof a proper impression of the tooth as well as enhancing and assuringthat substantially all of the retraction material is moved from thesulcus with the removal of the tooth cap.

FIGS. 19-23 illustrate another embodiment of the present invention. Inthis embodiment, a unique unit pre-dosed gingival retraction system 300is disclosed. A cap or dam 310 has a generally cylindricalconfiguration. The wall 312 has opposing cut out portions 314 forming ascalloped edge. Adjacent each scalloped edge or cut out portion 314 is afull height edge portion 320. External grooves 316 circumscribe a lowerportion of the cap 310. The grooves 316 permit easy handling, provide aplace on which to attach a retaining string, not shown, and provide somecompression compliance to the cap 310. Non-setting putty like material319 is placed within the cap 310.

FIGS. 20 and 21 illustrate in more detail the internal construction orconfiguration of the cap 310. Formed within the interior of the cap 310are a plurality of ridges 324 and slanted walls 326. Adjacent the openend of the cap 310, a tapered rim or edge 322 is formed. Adjacent thebottom closed end 330 of cap 310 is a bottom ridge 328 that forms agreater overhang or reduced diameter section than that of the ridges324.

FIGS. 22 and 23 more clearly illustrate the scalloped edge or cut outportion 314 and the full height edge portion 320 along the open end ofthe cap 310. The scalloped edges or cut out portions 314 and the taperedrim or edge 322 aids in positioning the cap 310 within the mouth of apatient and permits easier placement between adjacent teeth.

The cap 310 is preferably made of a flexible soft material such as astyrenic block copolymer material. One suitable material is sold underthe trademark DYNAFLEX by GLS Corporation located in McHenry, Ill., US.

The non-setting material 318 placed within the cap 310 has theproperties of providing sufficient flowability, yet sufficientresistance to pressure so as to fill the sulcus between the tooth andthe gum line resulting in effective and clean retraction of the gums.The material must also have the properties of sufficient adhesion to thecap 310 so as to permit removal of the cap 310 together with thematerial 318 remaining intact therein. The ridges 324 and bottom ridge328 greatly facilitate the retention of the material 318 within the cap310. The material 318 is preferably a dilatant material. A dilatantmaterial is a shear thickening fluid, which is one in which viscosityincreases with the rate of shear. A dilatant material may also be anon-Newtonian fluid. Additionally, a dilatant material may have theability to increase in volume when its shape is changed. The dilatantmaterial has flow characteristics that are desirable, and initiallyresist flow. The table below illustrates the preferred general formulafor the material 318 placed within the cap 310.

PERCENT BY WEIGHT MATERIAL 10 to 30% Polydimethylsiloxane 9 to 20%Astringent or hemostatic agent, such as aluminum chloride, aluminumpotassium sulfate, aluminum sulfate, alum, or ferric sulfate, or otherknown retraction agents that have hemostatic and astringent properties,or an astringent that also has hemostatic properties 1 to 10% Siliconeoil 1 to 75% Dilatant silicone 5 to 20% Potassium polyacrylate

In a preferred formulation, the non-setting material 318 comprises 30%polydimethylsiloxane; 9 to 10% hemostatic or astringent agent such asalum, aluminum sulfate, aluminum chloride, ferric sulfate; 1 to 2%silicone oil; 58 to 68% dilatant silicone; and 10% potassiumpolyacrylate. In yet another preferred formulation, the non-settingmaterial 318 comprises approximately 15% polydimethylsiloxane, 10%astringent or hemostatic agent, 1% silicone oil, 74% dilatant silicone,and 10% potassium polyacrylate. In yet another preferred embodiment, thenon-setting material 318 comprises 63 to 68% polydimethylsiloxane, 10%astringent or hemostatic agent, 2% silicone oil, 10% dilatant silicone,and 5 to 10% potassium polyacrylate. Hemostatic or astringent agentssuch as aluminum potassium sulfate, ammonium alum, ammonium alumdodecahydrate, as well as others may be used. Additionally, potassiumpolyacrylate is a hydrophilic material that absorbs water. Otherhydrophilic materials may be used, such as sodium polyacrylate or otherpolyelectrolytes.

A non-setting material of the above identified formulation has beenfound to have advantageous properties in permitting the cap 310 to bepre-filled with the non-setting material that is relatively stable andcan be prepackaged for easy use by a dentist. The non-setting materialresists excessive flow and yet conforms to the gum line so as to provideeffective retraction of the gum tissue away from the tooth with aminimum of effort and discomfort. Therefore, the present inventionprovides an easy, simple to use device that is convenient for thedentist, making dentistry easier.

After filling the cap 310 with the non-setting material 318, thematerial 318 may be dusted with a powder material 317 comprisingapproximately 75% polyacrylate and 25% of an astringent agent such asalum, or its equivalent.

FIGS. 24 and 25 illustrate another embodiment of the invention. In thisembodiment, a unit dose retraction system having a safety tab and madeof a porous material 400 is illustrated. The retraction system 400comprises a cylindrical wall 412 made of a porous material. Within thecylindrical wall 412 is placed a softer or more compressible porousmaterial 411. The cylindrical wall 412 is less compressible than theporous material 411. On an exterior surface of the wall 412 is a groove416. At the bottom of the wall 412 is a safety tab 432 having a hole 434therein. A string or cord 436 may be conveniently tied to the tab 432 asa safety feature in the event a patient inadvertently swallows theretraction system 400. The wall 412 is made of a porous material thatcontains a retraction agent which may be or include an astringent orhemostatic agent 419 impregnated therein. The softer foam orcompressible porous material 411 is placed within the cylindrical wall412 and may also be impregnated with a retraction agent which may be orinclude an astringent or hemostatic agent 419. In this embodiment, theastringent or hemostatic agent 419 may be dried and reactivated uponapplying moisture. In The moisture may be applied either prior toplacement in a patient's mouth, or by being activated by the patient'ssaliva. In another embodiment the softer foam or compressible porousmaterial 411 may be impregnated with a dilatant non-setting material.The dilatant non-setting material may be of a formula similar to thatdescribed above for the material 318 illustrated in FIG. 20. Thecombination of the compressible porous material and the dilatantnon-setting material has been found to work particularly well inretracting gum tissue. It is believed that the combination of pressureand retraction agent facilitates the retraction of the gum tissue. Thecompressible porous material 411 may also aid in absorbing excess fluidthat may form around the teeth in the mouth. The porous material makingup the walls 412 is preferably more rigid than the porous material orfoam 411 contained therein. The softer porous material 411 conformsaround the tooth and applies pressure to the gingival sulcus, aiding inretraction of the gum. In this embodiment of the present invention, thecombination of porous materials facilitate application of a hemostaticor astringent agent together with the ability to absorb excess fluids,such as blood, that results in good retraction permitting the taking ofa better impression.

Another embodiment of the invention is illustrated in FIGS. 26 and 27.FIG. 26 illustrates a prepared cap 500 pre-dosed with an astringent orhemostatic agent. The prepared cap 500 is made of a porous material thatis resilient and hydrophilic. The porous material may be made of vinylacetate and is preferably an ethylene vinyl acetate copolymer. Theprepared cap 500 may be made of a fiber, foam, or sintered material. Theprepared cap 500 has cylindrical walls 512 with an open end having abevel 514. The bevel 514 is adapted to aid in applying pressure to thegingival or gum tissue and assist in retraction. The interior 520 iscylindrical and may have a slight taper. The prepared cap 500 ispre-dosed with an astringent or hemostatic agent 519 interspersed in theporous material of the cap 500. A solution is prepared containing asolvent of water or alcohol or other solvent and an astringent orhemostatic agent, such as aluminum sulfate, aluminum ammonium sulfate,aluminum potassium sulfate, aluminum chloride, ferric sulfate, ferricchloride, alum, tannic acid, or other well known astringent orhemostatic agent. The solution preferably comprises between five andthirty-five percent by weight astringent or hemostatic agent.

The prepared cap 500 may also comprise other shapes or forms, such as amultiple of prepared caps for fitting multiple teeth, for example asillustrated in FIG. 17 or an elongated cap with a longitudinal groove asillustrated in FIG. 2 or 7.

FIG. 27 illustrates the method of preparing and using a prepared cap usein retraction. Box 600 represents the step of creating a solution ofbetween five and thirty-five percent by weight of an astringent orhemostatic agent. Box 602 represents the step of saturating a porous capwith the solution. The saturating of the porous cap may be accomplishedby dipping the porous cap in the solution, or spraying or pouring thesolution on the porous cap. Box 604 represents the step of drying theporous cap forming a prepared cap. The step of drying may beaccomplished by air drying or heating in an oven at an elevatedtemperature, preferably approximately one-hundred and fifty degreesFahrenheit. Box 606 represents the step of preparing a tooth forrestoration. Generally, the restoration may be preparation for a bridgeor crown procedure which generally includes the taking of an impressionof the area surrounding the prepared tooth. Box 608 represents placingthe prepared cap over the prepared tooth. Box 610 represents applyingpressure to the prepared cap for between three and five minutes. Thepressure may be applied by the patient biting down on the prepared cap.Box 612 represents the step of removing the prepared cap from theprepared tooth.

This embodiment of the invention may be used in combination with otherretraction devices or methods. For example, conventional retraction cordmay be packed between the tooth and sulcus or gum tissue prior to use ofthe pre-dosed prepared cap. Additionally, the pre-dosed prepared cap maybe filed with a material to aid retraction of the gum tissue prior toplacement over the prepared tooth.

This embodiment of the invention has the advantage of being convenientand easy to use. The pre-dosed prepared cap may have the dry astringentor hemostatic agent reactivated by moisture in the oral cavity. Thisaids in the control of any fluids that may be present, including thecessation of bleeding. Additionally, the pressure applied and shape ofthe beveled edges of the pre-dosed prepared cap aid in separating orretracting the gum tissue as well as controlling bleeding.

While the preferred embodiments and methods of the present inventionhave been shown and described herein, it will be apparent to thoseskilled in the art that various modifications and variations may be madewithout departing from the spirit and scope of the invention as claimedherein.

What is claimed is:
 1. A dental retraction material for use in wideningthe gingival sulcus in a dental procedure comprising:polydimethylsiloxane, ranging between 10 to 30 percent by weight; anastringent or hemostatic agent, ranging between 9 to 20 percent byweight; silicone oil ranging from between 1 to 10 percent; dilatantsilicone, ranging between 1 and 75 percent by weight; and a hydrophilicagent ranging from between 5 to 20 percent by weight, whereby when thedental retraction material is placed in the gingival sulcus, thegingival sulcus is widened and fluid absorbed.
 2. A dental retractionmaterial for use in widening the gingival sulcus in a dental procedureas in claim 1 wherein: said hydrophilic agent is selected from the groupconsisting of potassium polyacrylate and sodium polyacrylate.
 3. Adental retraction material for use in widening the gingival sulcus in adental procedure comprising: polydimethylsiloxane, ranging between 63 to68 percent by weight; an astringent or hemostatic agent, ofsubstantially 10 percent by weight; silicone oil of substantially 2percent; dilatant silicone, of substantially 10 percent by weight; and apotassium polyacrylate ranging from between 5 to 10 percent by weight,whereby when the dental retraction material is placed in the gingivalsulcus, the gingival sulcus is widened and fluid absorbed.